Threshold Voltage Tuning in Multilayer MoS_2 Transistors via Fluorine-Based Plasma Treatment

摘要

Inherent n-type transport behaviors in molybdenum disulfide (MoS2) have been a challenge for power-efficient nanoelectronic devices. Here, we report on threshold voltage tuning of multilayer MoS2 transistors induced by counter-doping effects of fluorine-based plasma treatment. The incorporated fluorine ions (F-) with relatively strong electronegativity effectively attract the excess carriers, electrons in MoS2 layers. In order to directly observe and compare the effects of counter-doping, we fabricate bottom-gated multilayer MoS2 transistors using a conventional mechanical exfoliation method. The MoS2 transistors treated with CF4 plasma exhibit positive V-T(H) of 6.5 +/- 3.8 V and inverse proportionality to the MoS2 channel thickness. In comparison to molecular chemisorption doping, the plasma doping method, which is facile, controllable, and CMOS-process compatible, can be more universal approach for wafer-scale TMDs through further process optimization.